Obesity is a major health problem of serious concern in western nations. Despite considerable effort by the scientific and healthcare professions to understand and successfully treat obesity, its incidence continues to rise, and the obesity-related costs to society are staggering. Understanding how neuropeptides function in the brain and periphery to control food intake and body weight is crucial for solving the problem of obesity. The goal of this proposal is to identify the role of arcuate nucleus neuropeptide Y (NPY) in the anticipatory response to feeding. There is evidence that physiological and behavioral changes occur when individuals anticipate a meal in order to minimize its metabolic impact on the body. Many of the physiological and behavioral responses induced by NPY administration mimic the anticipatory responses associated with meals. The hypothesis of this proposal is that NPY, rather than functioning to increase food intake per se, is actually the central mediator of food-anticipatory responses. To test this hypothesis, this proposal has two specific aims. The first series of studies will determine the role of NPY in mediating the anticipatory response to feeding by assessing hypothalamic NPY gene expression and protein levels in anticipation of a nutrient load, and the second series of studies will utilize direct administration of NPY into the 3rd-cerebral ventricle to assess meal-anticipatory responses in the brain, periphery, and in behavior. [unreadable] [unreadable]